export function exitFullScreen() {
    if (document.fullscreenElement || document.mozFullScreenElement || document.msFullscreenElement || document.webkitFullscreenElement) { // 判断是否在全屏状态下
        if (document.exitFullscreen) {
            document.exitFullscreen();
        } else if (document.webkitExitFullscreen) {
            document.webkitExitFullscreen();
        } else if (document.mozCancelFullScreen) {
            document.mozCancelFullScreen();
        } else if (document.msExitFullscreen) {
            document.msExitFullscreen();
        }
    }
    return null;
}
